216 Miscellaneous Intelligence. 



crystallization to yield the ferro-prussiate of potassa, a mother 

 liquor remains which will not crystallize ; but, by slow evapora- 

 tion effloresces in greenish vegetations. This is a particular 

 modification of the cyanuret of iron and potassium, which is so- 

 luble in water, and on exposure to a moist air, becomes brown. 

 Its solution, when evaporated, yields small green scales ; and 

 these, when analyzed, so closely resemble in composition, the 

 yellov/ salt, that no conclusion can be drawn from the ex- 

 periment. . 



This salt may be converted into the yellow salt, by being 

 carefully fused in a close crucible; and when cold, dissolved in 

 water, the fluid will contain cyanuret of iron and potassa, hydro- 

 cyanate of potassa, and carbonate of potassa. Acetic acid will 

 decompose the two last salts, the solution is to be evaporated 

 and acted on by alcohol, the double cyanuret is then thrown 

 down ; it may be collected, dissolved, and crystallized. 



Barytes, by acting on prussianblue, also forms the green com- 

 pound. Lime produces very little of it, but ammonia forms it 

 in such abundance, that sometimes nothing else is obtained. It 

 then crystallizes in small green needles. Its solution is preci- 

 pitated by alcohol as a sirup ; during evaporation, it deposits a 

 green powder, and by long exposure to the air, is in a great 

 measure decomposed. Annates de Chimie, xv. pp. 144, 225. 



14. lire's Chemical Dictionary. — Dr. Andrew Ure, of Glasgow, 

 has just published " A Dictionary of Chemistry, on the basis 

 of Mr. Nicholson's ; in which the principles of the science are 

 investigated anew, and its applications to the phaenomena of Na- 

 ture, Medicine, Mineralogy, Agriculture, and Manufactures, de- 

 tailed." We regret that the length of our observations on Dr. 

 Thomson's System of Chemistry have prevented an extended 

 notice of this work, in its proper place, and which we are obliged 

 to reserve for a future Number. It is a work which displays 

 considerable diligence, and equal knowledge of the subjects of 

 which it treats, and will prove a valuable addition to the stu- 

 dent's library. 



III. Natural History. 



^. Geology, Mineralogy, Meteorology, J^c. 



1. Avery valuable work has just been published by Dr. Mac 

 Culloch, entitled, " A Geological Classijication of Rocks, with 

 descriptive Synopses of the Species and Varieties, comprising the 

 Elements of Practical Geology." Upon a future occasion we 

 propose to discuss the merits of this book more at length, and 

 shall therefore confine this notice to a bare sketch of its 

 contents, from Avhich, however, our geological readers will be 

 able to draw some conclusions respecting its interest and 



